Fuel pump with turbulence reducing inlet dome



July 11. 9 F. .1. SCHiMMELPFENIG 3,330,216

FUEL PUMP WITH TURBULENCE REDUCING INLET DOME Filed June 1, 1965 j? [N VENTOR.

flak/m1 J' Sui/212711402 United States Patent 3,330,216 FUEL PUMP WITH TURBULEN CE REDUCING INLET DOME Frederick J. Schimznelpfenig, Davison, Mich, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed June 1, 1965, Ser. No. 466,087 4 Ciaims. (Cl. 103150) ABSTRACT OF THE DISCLOSURE A diaphragm type liquid fuel pump having a fuel inlet connection dampening pressure pulsations to improve fuel flow.

SPECIFICATION This invention relates to fuel pumps and more particularly to fuel pumps of the diaphragm type such as are used on automobiles.

It has been customary in the past to employ air domes for the inlets of many reciprocating diaphragm fuel pumps, the purpose in mind being to minimize pulsations in the pump flow and thereby increase and smooth out the pump discharge. Such a pump is disclosed in the U.S. Patent 2,419,775 granted Apr. 29, 1947, in the name of William H. Hazard.

It has now been found that the use of an apertured tube in an air inlet dome with the aperture of the tube directed downwardly toward the inlet valve leading to the diaphragm pumping chamber results in a pronounced increase in the liquid flow through the pump and as compared with air inlet domes as employed heretofore in this field.

An object of the present invention is to provide an improved fuel pump of the diaphragm type in which the pulsations are dampened and the flow is not disrupted or impeded by undue turbulence.

A feature of this invention is a diaphragm type fuel pump in which an apertured inlet tube is so located in an air inlet dome as to direct flow toward the inlet valve without disturbing the air or vapor trapped in the dome.

This and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings:

FIGURE 1 is an elevation and part sectional view of a fuel pump as one embodiment of the present invention and as supported for operation of an automobile engine; and

FIGURE 2 shows a modification of the inlet dome arrangement of FIGURE 1.

In FIGURE 1 of the drawings, a portion of an automobile engine is shown as a support for a fuel pump body 12 which is attached to the engine 10 as by bolts 14. As is conventional in automobile pumps, the body 12 has a passage 16 in which is mounted a pivot pin 18 and on this pin a rocker arm 20 is adapted to be oscillated by some portion of the engine such as a cam on the camshaft. As will be understood and which is conventional in fuel pumps, the rocker arm 20 is adapted by means of two cooperating backing plates 24 and 26 to reciprocate a pumping diaphragm indicated at 30. This diaphragm has its periphery clamped between a rim of the pump body 12 and a pump cover generally indicated at 32. The pump cover is composed of an upright sheet metal dome 34 in the form of an inverted cup, an outer shell 36 which is crimped as at 38 to the pump body 12 tightly to retain the diaphragm as well as the periphery of an inner shell 40. The outer shell 36 retains the dome 34 by means of a brazed and tight joint as at 42.

3,330,216 Patented July 11, 1967 The inner shell 40 bears an aperture 44 in alignment with an aperture 46 in the outer shell 36 so that a oneway inlet valve 50 supported by the inner shell 40 is in alignment with both apertures 44 and 46. The valve 50 is not specifically described herein as it is conventional but it will be appreciated that when suction is induced between the diaphragm 30 and inner shell 40 by reciprocation of the diaphragm 30, the one-way inlet valve 50 will open and when the pressure in the pumping chamber 60 increases, the inlet valve 50 will close.

An inlet tube 54 extends into the dome 34 and the length of the tube substantially traverses the full width of the pulsator chamber formed by that dome but its width is less than that of the pulsator chamber. It will be seen in FIGURE 1 that the tube 54 is open at its end 56. An aperture 58 is formed in the bottom side of the tube 54 and this aperture faces or is directed toward the inlet valve 50.

The inner shell 40 of the cover 32 not only defines the pumping chamber 60 with the cooperation of the diaphragm 30 but it also cooperates with the outer shell 36 in forming outlet chamber 62. A sealing washer 37 insures separation of the pump inlet flow from the outlet chamber 62. Communication between the pumping chamber 60 and the outlet chamber 62 is by Way of a conventional one-way outlet valve 63. Flow from the outlet chamber 62 of the pump is by way of a fitting 64 and a discharge tube 66.

Cars with a high underhood temperature sometimes require a vapor diverter for satisfactory operation, that is, to avoid vapor lock of the fuel system. The pump disclosed in FIGURE 1, therefore, preferably has the fuel outlet fitting 64 extend down into the lower portion of the outlet chamber 62 where the solid or liquid fuel collects. A small opening is located at the top of the outlet chamber 62 and through which vapors that collect above the lower end of the fitting 64 may pass back by means of a conduit 82 to the fuel tank.

In FIGURE 2, a slight variation in the structure is seen in that the dome 34 is fitted with a difierent inlet tube 84. This tube has an aperture 86 similar to the aperture 58 in FIGURE 1 but in this case the end of the tube 84 is closed off as at 88.

The dome 34 serves to increase liquid fuel flow through the pump by trapping air and fuel vapors in its top. This air and vapor in the dome is such as substantially to reduce the pressure and vacuum peaks thereby allowing the valves 59 and 63 to follow the strokes of the pump more effectively.

The tube 54 or 84 helps to maintain the vapor or air inside the dome 34 and reduces the turbulence in the liquid fuel which would otherwise occur and serve to disturb the air or vapor pocket in the dome 34. This reduction of turbulence definitely improves the liquid flow rate through the pump as has been determined by experimentation. Wide variations of tube designs, tube end termination points and tube angles with respect to the inlet valve 50 axis have been tested departing from those disclosed in the drawings but of all those tested, the substantial increase in liquid flow was obtained only by the tube inlet designs disclosed. In comparing the various inlet tube designs, no changes other than in the tube inlets were made in the pumps undergoing tests but it is understood that the same advantages are obtained using the inlet arrangement of the present invention if the outlet fitting 64 were changed also to embody a dome and inlet tube as employed with regard to the inlet valve, i.e., many variations may be made in the outlet arrangement without adversely affecting the performance of the tube 54 or 84 with respect to the inlet valve and dome 34.

I claim:

1. A diaphragm type fuel pump in which a diaphragm and a pump cover define a pumping chamber, inlet and outlet one-way valves retained in said cover, a dome forming a pulsator chamber leading to the inlet side of said inlet valve, an inlet tube extending into said dome and having a diameter less than the width of said pulsator chamber, one side of said inlet tube facing said pulsator chamber, and an aperture in the other side of said inlet tube directed toward said inlet valve.

2. A diaphragm type fuel pump in which a diaphragm and a pump cover define a pumping chamber between them, inlet and outlet one-way valves retained in said cover of said pumping chamber, a dome forming a pulsator chamber leading to the inlet side of said inlet valve, an inlet tube forming a wall partially closing off said pulsator chamber and having an open end, and an aperture in the side of said inlet tube facing and directed toward said inlet valve.

4 pulsator chamber, and an aperture in the opposite side of said inlet tube directed toward said inlet valve.

4. An upright diaphragm type fuel pump in which a diaphragm and a pump cover are clamped together to define between them a pumping chamber, inlet and outlet one-way valves retained in said cover to control fuel flow through said chamber, a vertically extending dome forming a pulsator chamber at the top of said pump and leading to the inlet side of said inlet valve, an inlet tube of smaller width than that of said pulsator cham-' ber extending horizontally and into said dome, an aperture in the bottom side of said inlet tube in alignment with the axis of said inlet valve and coaxial with the latter, and the top side of said inlet tube facing said pulsatoi' chamber.

References Cited UNITED STATES PATENTS 2,419,775 4/ 1947 Hazard 103 224 2,901,176 8/1959 Hoyt 103224 2,955,671 10/1960 Leistritz 18148 3,148,745 9/1964 Jones 103-224 3,188,975 6/1965 Sprayberry et a1. 181- 47.1 3,236,383 2/1966 Smith et al 103-450 ROBERT M. WALKER, Primary Examiner.

DONLEY I. STOCKING, Examiner,

W. L. FREEH, Assistant Examiner. 

1. A DIAPHRAGM TYPE FUEL PUMP IN WHICH A DIAPHRAGM AND A PUMP COVER DEFINE A PUMPING CHAMBER, INLET AND OUTLET ONE-WAY VALVES RETAINED IN SAID COVER, A DOME FORMING A PULSATOR CHAMBER LEADING TO THE INLET SIDE OF SAID INLET VALVE, AN INLET TUBE EXTENDING INTO SAID DOME AND HAVING A DIAMETER LESS THAN THE WIDTH OF SAID PULSATOR CHAMBER, ONE SIDE OF SAID INLET TUBE FACING SAID PULSATOR 